Many electronic components, such as integrated circuits, are packaged by mounting a die onto metal electrical contacts, and subsequently encapsulating the die and part of the contact structure in a polymer material. The metal contacts are partially stamped from a flat strip of metal with a web of metal left in the strip to retain and register the contacts during the manufacturing process. These strips are sometimes called “lead frames.” The strip typically has guide holes on the edges to accurately control its position as it passes through the various pieces of assembly equipment. Once the assembly is complete, the completed device is cut from the lead frame by a punch and die operation (“singulation”) and the contacts bent into their final shape. The individual devices are then tested in test sockets which are designed to hold a single component.
With the miniaturization of components, it is now possible to build hundreds of components on a single lead frame structure. This provides a significant cost reduction in the manufacturing process, but introduces a serious handling problem once the small parts have been singulated from the lead frame. This can result in the dropping of parts causing reduced yield through the testing and packaging process. The invention herein makes it possible to test the components while still in the lead frame, and thus reduce part loss during the testing stage.
Anisotropic Conductive Elastomer
Anisotropic Conductive Elastomer (ACE) is a composite of conductive metal elements in an elastomeric matrix that is normally constructed such that it conducts along one axis only. In general this type of material is made to conduct through its thickness. Anisotropic conductivity is achieved in one form of ACE by mixing magnetic particles with a liquid resin, forming the mix into a continuous sheet and curing the sheet in the presence of a magnetic field. This results in the particles forming multiple separate but closely-spaced electrically conductive columns through the sheet thickness, each column separated from the others by cured insulating resin. Another group of ACE materials is constructed by embedding fine wire in a polymer matrix. The resulting structure has the unique property of being both flexible and anisotropically conductive. These ACE materials can be constructed in large, continuous sheets, which can provide separable electrical interconnection over an extended area.